As for speaking to a tulpa in general, I wouldn't regard Gray speaking to Ranger as Gray speaking to God. I would struggle with suggesting Gray speaking to me about something unrelated to God as well. However, I have another form I can "transform" into and I feel as if I am one with God. In this state, I feel like this should be prayer.
How do you talk to God? Can you expect a voice to speak back? Can you visualize God? I feel like you should be able to do those two things. It feels more natural, real. If prayer is a conversation, shouldn't there be two participants?
Gray concluded a tulpa is not God, and him speaking to me was a mistake. I think some of this was rooted in regret, he said things to me not knowing he could hurt me. However, I don't think Gray should have said those things to God anyway...